Seven members of the National Ballet of Cuba defected last month while on a performing tour in Mexico, according to a dance official on the island.

The source, who lacked authorisation to discuss the matter publicly and spoke on condition of anonymity, confirmed the defections but did not offer details, saying only that "there were seven who did not return".

The defections were received with sadness in Cuban ballet circles. "It pains us," said Ramona de Saa, director of Havana's National Ballet School, where six of the dancers were trained.

Saa added she considered one of the ballerinas, whom she did not name, to be like a daughter.

"It is the most difficult decision I have made in my life, but we're not thinking about the past but rather the future," the website quoted Ruiz Diaz as saying. "We were intent on seeking a better artistic life and economic wellbeing for our families."

The National Ballet, a source of pride for Cuban officials, has trained many world-class dancers. However, it has experienced a number of high-profile defections over the years as performers are lured overseas by the promise of greater creative and economic opportunity. In March 2011, five members stayed in Canada after a performance.

For Cuban officials, defections by the likes of dancers, athletes and doctors are bitter betrayals. Communist authorities lament what they deem to be a theft of talent that they train for free but at great cost to the government.

Saa said defecting dancers often overestimated their chances of succeeding abroad and seldom found a company to take them on. "We are privileged," she said. "In the world, the situation of ballet is very difficult."